Abstract

The aim of this study was to evaluate the VO2max, peak blood lactate and peak heart rate among wheelchair basketball and rugby players. Thirty-eight wheelchair basketball and rugby players were purposively selected based on the following criteria: aged 18-50 years, actively involved in a wheelchair sport for at least one year prior to the study and had at least a minimum of 10% loss of function in the lower extremities. Results indicated that the paraplegics had a higher absolute peak VO2 when compared with the quadriplegic groups. When percentage differences were compared, it was evident that the “other” group (34%) and the paraplegic group (27%) were above the average group mean (1564.3 m?/min-1), whilst the other two groups were (21% and 15%) below the group mean, respectively. The results of the study have practical implications for players’ health and sport performance. It is important that athletes suffering from spinal cord injury or any other type of physical impairment establish some type of anaerobic/aerobic fitness specific to their sport. For disabled athletes, sport participation is imperative for optimising their health, functional ability and physical performance.

Keywords

Introduction

Wheelchair basketball is played by athletes who have a
physical disability that prevents running, jumping and
pivoting, such as paraplegia, amputations, or joint and
musculoskeletal conditions [1]. On the other hand,
wheelchair rugby is played by individuals who have a
disability which affects the normal functioning of the
arms and legs [2]. Previous studies [3-5] have shown
that aerobic endurance fitness is important for wheelchair
games’ players. VO2max (aerobic capacity) is an attribute
required for success in endurance-related events [6]. Data
on aerobic fitness of wheelchair players have been
reported in the literature [3,5]. However, there appeared
to be differences in the VO2max of athletes in terms of
gender, age, type of disability, and sports. For instance, a
study by Bhambhani, Holland, Erickson and Steadward
[7] investigated physiological responses during
wheelchair racing in which quadriplegics were compared
to paraplegics. Bhambani et al. [7] found the peak values
of VO2, and HR obtained during incremental velocity
wheelchair exercises tended to be significantly higher in
paraplegics than quadriplegics. The authors did not find
any significant differences between these groups for oxygen pulse (oxygen utilisation per heart beat).
However, another study by Eriksson, Lofstrom and
Ekblom [8], found aerobic power during maximal
exercise in trained and untrained quadriplegics and
paraplegics. A significant difference was found in which a
38% increase in peak VO2 was noted in the trained
athletes. They concluded that peak VO2 values in well
trained quadriplegic athletes were comparable to those of
untrained paraplegics with a low-level injury and that
physical training could largely reduce the differences in
aerobic capacity between quadriplegics and paraplegics
[8]. In the study conducted by Mclean, Jones and Skinner
[9], 11 individuals with quadriplegia were tested of which
six were classified as high-level quadriplegics (lesion at
C7 and above) and five, low-level quadriplegics (lesion
from C7 and below) and found peak power output, VO2 and ventilation to be 16%, 15% and 18% higher in the
supine position. According to McLean et al. [9], another
possibility for the increased peak VO2 in the supine
position was the gravitational pull on the abdominal
contents which could not be opposed by contraction of the
paralysed abdominal musculature. During wheelchair
ergometry, Huonker et al. [10] reported that the peak VO2 in able-bodied individuals was 32% higher than that of untrained individuals with paraplegia but 10% lower than
that found in trained athletes with paraplegia. The oxygen
pulse was lower in the untrained individuals with
paraplegia by 20%, with no difference observed between
the able-bodied individuals and the athletes with
paraplegia.

To our knowledge, there is hardly any study that has
assessed peak VO2 among physically impaired athletes
with a wheelchair ergometer. Therefore, this study was
primarily conducted to examine the VO2max among
wheelchair basketball and rugby players. It was also of
interest to the study to assess the players’ peak blood
lactate and peak HR as predictors of peak fitness.

Methodology

Sample

The sample of this study consisted of 38 purposively
selected male basketball and rugby wheel chair players.
The participants were categorized according to their
physical disabilities as follows: 13 polio (34 %), 8
paraplegics (21 %), 8 quadriplegics (21 %) and 9 others
(24 %). Participants were chosen based on the following
criteria: aged between 18-50 years, actively involved in a
wheelchair sport for at least a year before the study and
had at least a minimum of 10% loss of functional ability
in the lower extremities.

Procedure

Prior to data collection, permission to carry out the study
was granted by the Tshwane University of Technology
Higher Degree Ethics Committee. All the athletes were
fully informed about the risks associated with the project
and signed an informed consent form. Due to the nature
of the athletes being tested, they were all fully screened
by a physician prior to the study. Peak VO2 testing was
done in the human performance laboratory at Tshwane
University of Technology under supervision of the lead
author and his co-supervisors.

The ergometer was calibrated with special weights before
each peak VO2 test was performed. An electronic display
board was placed in front of the participant when he was
seated in the ergometer. This electronic board displayed
the athletes’ heart rate and propulsion velocity measured
in revolutions per minute. Once the athlete was seated in
the wheelchair ergometer, he was strapped in to assure
stability, and also to prevent him from generating power
from the pelvis area rather than from the upper body.

The following protocol was used during the testing:

• the players were required to propel at a constant
speed of 32-RPM throughout the test;

• a warm-up set of three minutes was allowed at zero
resistance;

• every three minutes thereafter the flywheel
resistance was increased in increments of 30-watts; and

• the test was terminated if the set speed (32-RPM)
could not be maintained or due to volitional
termination.

The wheelchair ergometer was connected to a Med
Graphics system ® (Med Graphics Corp, St Paul
Minnesota, USA). Manual calibrations of gas analysis
were performed prior to each test to ensure that the
correct amount of oxygen concentration was recorded.
Athletes were required to wear a portable face mask
which measured their expired oxygen and carbon-dioxide
flow. A face mask was used to attach the mouth piece
which analyzed the amount of airflow that the athlete
generated during the test. Athletes had to inhale and
exhale through their mouths as the face mask prevented
them from breathing through their noses. During the peak
VO2 test, verbal encouragement was given to all the
athletes to help them maximize their performances. After
every three minutes, RPE (rating of perceived exertion)
was taken using the Borg’s scale. This scale is a sound
predictor of fatigue in the arms (local), and at the chest
(lung) area. Exercise heart rate was measured by means of
an Accurex Plus ® heart rate monitor. Resting exercise
heart rates’ were taken, and every three minutes thereafter
during the peak VO2 test. Post-exercise values were
obtained up until nine minutes. The age predicted
formula (220bpm/min-age) was used to examine whether
the participants reached their peak HR values. Blood
lactate values were obtained by means of an Accusport ®
(Boehringer Mannheim, Belgium) (BM) lactate metre.
Lactate strips and Softclix II (Softclix II ® lancets) were
used to measure blood lactate concentrations. Resting
values were recorded and every three minutes thereafter
during the peak VO2 test until exhaustion. Post-exercise
values were recorded up to nine minutes.

Results and Discussion

As shown in Figure 1 the paraplegics had a higher
absolute peak VO2, when compared with the quadriplegic
groups. Comparing percentage differences (Table 1), it
was evident that the “other” group (34%) and the
paraplegic group (27%) were above the average group
mean (1564.3 ml/min-1), whilst the other two groups were
(21% and 15%) below the group mean, respectively.

Eriksson et al. [8] found that peak VO2 values during
maximal exercise increased with lower levels of spinal
cord injury, indicating that paraplegics had a higher peak
VO2 than quadriplegics. Bhambhani et al. [7] also
reported similar results when peak VO2 was compared
between paraplegics and quadriplegics. Figure 1 demonstrates that the “other” group displayed the highest
absolute peak VO2 values (2182.7 ml/min-1). This
phenomenon can be attributed to the fact that this group
did not consist of any SCI athletes. Thus more muscle
mass was utilised and the redistribution of blood flow was
enhanced [11].

Figure 2 illustrates the average and maximum values of
absolute peak VO2 and blood lactate concentration
between the different groups. Some differences existed
between the quadriplegic group and the rest of the groups.
Initial blood lactate concentration values were the same
for all the groups but these increased concomitantly with
absolute peak VO2 values. The quadriplegic group
displayed the lowest absolute peak VO2 (1065.38
ml/min) and blood lactate concentration (3.6 mmol). The
low levels of blood lactate concentration could be
attributed to low functional muscle mass in quadriplegics
[8]. It should be noted that in Figure 3 the values of the
paraplegic and polio groups followed a similar pattern and then plateau, whereas data for the “other” groups
showed a steady increase until the end of the test.
Therefore, there seemed to be a linear relationship
between absolute peak VO2 and blood lactate
concentration in this category.

The paraplegic group had a higher absolute peak VO2 than the quadriplegic group, which is consistent with the
findings of Eriksson et al. [8] who noted that peak VO2 values during maximal exercise increased with lower
levels of spinal cord injury, suggesting that paraplegics
had a higher peak VO2 than quadriplegics

A graphic illustration of average and maximal peak VO2
and HR values is presented in Figure 3. Bar-Or and Nene
[12] noted that there was no linear relationship between
HR and peak VO2 in the individuals they tested who had a
lesion above the third thoracic level (T3). In contrast, this
study revealed that a linear relationship existed between
absolute peak VO2 and HR (Figure 3). Between all the
groups, the HR increased as the absolute peak VO2 increased, which gave an indication of linearity. Similar
to this finding, Bar-Or and Nene [12], Jehl et al. [13],
Hooker et al. [14] and McLean et al. [9] concluded that
there was a linear relationship between HR and peak VO2 in individuals with spinal cord injury. The polio group
and the “other” group displayed the highest average HR
values (184 b/min and 187 b/min), respectively.

Limitation

Scientific literature on aerobic characteristics of
wheelchair athletes is sparse. Therefore, access to more
recent literature on the subject was difficult to find.
Furthermore, it is desirable to collect the data on larger
samples of wheelchair athletes, but this was not feasible
as they are usually found in relatively small numbers.
These limitations should be considered in interpreting the
findings of this study.

Conclusion

It is important that athletes suffering from spinal cord
injury or any other type of physical impairment establish
some type of anaerobic/aerobic fitness specific to their
sport. This study found that paraplegics reported a higher
absolute peak VO2, when compared with the quadriplegic
groups. For disabled athletes, sport participation is imperative for optimising their health, functional ability
and physical performance.